O'Farrell says he backs gay marriage

NSW Premier Barry O'Farrell has come out in favour of same-sex marriage, labelling claims that it undermines the institution of marriage as "utterly ridiculous".

Mr O'Farrell declared his support for a change to the Marriage Act in the wake of the New Zealand parliament's vote to legalise same-sex marriage, Fairfax Media reports.

New Zealand is the 13th country to legalise gay marriage and the first in the Asia-Pacific.

Fairfax Media reports Mr O'Farrell would prefer federal parliament to change the Marriage Act, but is prepared to go it alone if a parliamentary inquiry in NSW finds the state can act by itself.

The premier reportedly believes the issue boils down to family.

"My view - a view that I've come to in recent years - is that as a Liberal who believes that commitment and family units are one of the best ways in which society is organised, I support the concept of same-sex marriage," Mr O'Farrell told Fairfax Media.

"Ultimately, people caring for each other works side by side with governments to create better communities."